Crystalline Cellulose in Hydrated Primary Cell Walls of Three Monocotyledons and One Dicotyledon |
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Authors: | Smith, Bronwen G. Harris, Philip J. Melton, Laurence D. Newman, Roger H. |
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Affiliation: | 1 School of Biological Sciences, The University of Auckland Private Bag 92019, Auckland, New Zealand 2 Food Science, University of Otago Dunedin, New Zealand 3 Industrial Research Limited P.O. Box 31-310, Lower Hutt, New Zealand |
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Abstract: | The molecular ordering of cellulose, including its crystallinity,in the unlignified primary cell walls of three monocotyledons(Italian ryegrass, pineapple, and onion) and one dicotyledon(cabbage) was characterized by solid-state 13C NMR spectroscopy.These species were chosen because their primary cell walls havedifferent non-cellulosic polysaccharides and this may affectthe molecular ordering of cellulose. Values of the proton rotating-framerelaxation [T1p(H)] and spin-spin relaxation [T2(H)] time constantsshowed that the cellulose in the cell walls of all four specieswas in a crystalline rather than an amorphous state. Furthermore,a resolution enhancement procedure showed that the triclinic(I) and the monoclinic (Irß) crystal forms of cellulosewere present in similar proportions in these cell walls. However,the calculated cross-sectional dimensions of the cellulose crystallitesvaried among the cell walls (in the range 23 nm): thelargest were in the Italian ryegrass, the smallest were in theonion and cabbage, and those of intermediate size were in thepineapple. The crystallite dimensions may thus be affected bythe non-cellulosic polysaccha-ride compositions of the cellwalls. 4Present address: Food Science Postgraduate Programme, Departmentof Chemistry, The University of Auckland, Private Bag 92019,Auckland, New Zealand. |
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